Rigidity and flexibility of sexuality

When people think of sexuality, they think of a partnership between one man and a woman. We always thought that having one partner is what's desirable within a relationship. However, some people prefer to have multipartners. Those people who prefer to have multipartners should be allowed to have some because we all have different desires. Maybe this idea will help reduce a number of divorces in our society. Because people get tired to be with one person all the time. That is why a number of divorces are so high. Why people resist multipartners when it comes to heterosexuality? I hear that homosexuals have no limits when it comes to partners they can have. I mean man involved in homosexuality tend to be opened to multisexual partners. But when it comes to a woman and man involved in a relationship, multipartners are not allowed. The reason might be that women are policing their partner to have only one relationship. Could it be the reason why so many marriages results to devorce? Because man or sometimes woman become unhappy with a single partner. If that is the case we need to re-examine the rigidity and flexibility of the relationships in this present day.